The utility company said the device "was specifically installed to protect the Mercedes-Benz Superdome equipment in the event of a cable failure between the switchgear and the stadium."

A statement from the company said: "While the relay functioned without issue during a number of high-profile events -- including the New Orleans Bowl, the New Orleans Saints-Carolina Panthers game, and the Sugar Bowl -- during Sunday's game, the relay device triggered, signaling a switch to open when it should not have, causing the partial outage.

"This device has since been removed from service and new replacement equipment is being evaluated."

Entergy officials and the firm that manages the Mercedes-Benz Superdome appeared before the New Orleans City Council’s Utility Committee Friday. The emergency meeting was called in the wake of the 34-minute power outage, which occurred early in the second half of the championship game between San Francisco and Baltimore.

Entergy New Orleans CEO Charles Rice told committee members that the device "for some unknown reason at this particular time, did not react the way that it should."

Rice said the company was continuing to work with the equipment's manufacturer to determine what caused it to malfunction.

Cynthia Hedge-Morrell, the committee's chairwoman, struck a measured tone throughout the proceeding, which was attended by five city councilmembers. "I would like to stress this is a fact-finding meeting, not in any manner to be constructed in a laying of fault or blame on any one entity regarding this outage," Hedge-Morrell said at the beginning of the meeting.

Doug Thornton, the senior vice president for SMG, the management company that operates the Superdome, said Friday that he was certain early on that the outage was not caused by too much demand for power on the stadium's electrical system.

"We were well within the capacity" during Sunday's game, Thornton said.

Immediately after the outage, Entergy had said all its equipment was working properly, and the issue must have been caused by the Superdome. But later Sunday, Entergy and SMG issued a joint press release saying that an investigation was being launched to identify the problem.

Nola.com|The Times-Picayune reported Monday that the preliminary investigation was pointing to the relay equipment, called a switchgear, and whether it had failed or was triggered by something else in the system.

Fearful of a blackout not unlike one that marred a nationally televised San Francisco 49ers game in late 2011, officials from Entergy and the Superdome had embarked on a last-minute, multimillion-dollar effort to ensure such a spectacle wouldn’t be repeated at this year’s Super Bowl.

Early indications were that the 11th-hour upgrades to the Dome’s electrical system, intended to bolster the stadium’s electrical reliability, may have contributed to the nationally televised outage that left New Orleans feeling a bit sheepish in the afterglow of the big game.

In December, a little more than a month before the Super Bowl, Entergy New Orleans was finishing a $4.2 million upgrade to the stadium’s electrical system, changing it from "redundant" to "tertiary” — meaning the stadium would now be served by three feeder lines rather than two. As that job neared completion, Superdome officials tested their own power lines and found the equipment had “some decay and had a chance of failure.”

An engineer hired by the Louisiana Stadium and Exposition District, the public agency that owns the Dome, warned in October that the stadium’s main power feed was “not sufficiently reliable to support the high-profile event schedule.”

“Failure of this system will result in loss of events and extreme financial liability to the State, LSED and SMG," the firm that manages the Superdome, David Stelly of the Lafayette engineering firm Associated Design Group said in a report.

The Dome’s overseers quickly authorized a rash of repairs, with work wrapping up in late December.

The switchgear controls the flow of electricity from the power company to the stadium.

The equipment, added as part of the upgrades, automatically shuts down when a problem is detected, such as a surge or loss of electricity, potentially signaling — and protecting — against a more protracted power outage.

Thornton said Monday that the switchgear "sensed an abnormality" and tripped.

Entergy's statement Friday indicates that the switchgear failed in some way, but it is not yet clear what caused the failure.